1. Field of the Invention
The invention relates to a video apparatus which can output video/audio signals in a plurality of formats and to a control method of outputting an image signal in such a video apparatus.
2. Description of the Related Arts
In recent years, video apparatuses such as a video camera apparatus and the like have remarkably been widespread. A use form in which a motion image or a still image recorded in a recording media such as tape, disk, or the like by the video apparatus is outputted to a computer such as a personal computer or the like or a television apparatus and monitored is also being generalized. Such a monitoring form is realized merely by connecting the video apparatus and the computer or the like with a predetermined cable and executing a predetermined simple operation.
Functions of the video camera apparatuses which have remarkably been spread as mentioned above are also remarkably being improved. For example, an apparatus of a model in which video/audio signals of different formats can be mixedly recorded into the same recording media has also been proposed. As an example of such a video/audio signal format, a combination of a DV (Digital Video) format and an HDV (High Definition Video) (registered trademark) format can be mentioned.
The DV format is a recording format which is widely used in commercially available video camera apparatuses and data is compressed data fixed rate of about 3.5 Mb/sec. Video quality can be made as close as possible to the quality of a broadcasting level as close as possible owing to such a compression rate. Since video/audio data is converted into digital data and recorded onto a tape, it can be copied into a disk device of the computer through the cable or its backup copy can be recorded onto the tape without causing a deterioration in quality which occurs in an analog copy. A recording media which is used in the video camera apparatus using such a recording format is a DV cassette tape or a mini DV cassette tape. According to the mini DV cassette tape, it is physically smaller than the DV cassette tape and a recording possible time is shorter.
In the HDV format, there are a 720p (progressive) system and a 1080i (interlace) system and the recording and reproduction of a high fine HD (High Definition) video image can be executed. A video format is MPEG2 (Moving Picture Experts Group phase 2). The data is compressed at a rate of about 19 Mb/sec in the case of the progressive system or about 25 Mb/sec in the case of the interlace system.
According to the HDV standard, since the same cassette, tape speed, and track pitch as those of the DV standard are used, compatibility with articles of the DV standard is high. More specifically speaking, it is possible to add the recording/reproducing function according to the HDV format to the video camera apparatus of the DV standard and record the video/audio signals of both formats onto one tape or the like.
However, if such a video camera apparatus corresponding to both of the DV format and the HDV format is connected to the computer via a cable specified by, for example, IEEE (The Institute of Electrical and Electronics Engineers, Inc.) 1394 (IEEE1394 cable) and the format of the output image (reproduction image) is switched during the reproduction, there is a case where such a problem that the computer side hangs up occurs.
Such a problem occurs by the following reason: that is, when the computer is connected to the video camera apparatus by the IEEE1394 cable, a dedicated driver of the format used by the video camera apparatus (which is being reproduced at this point of time) is read, and after that, transmission and reception of the data to/from the video camera apparatus are executed through such a driver for a period of time during which they are connected by the IEEE1394 cable.
That is, when the computer is connected to the video camera apparatus by the IEEE1394 cable, whether the video camera apparatus corresponds to the DV format or the HDV format (MPEG2) is discriminated on the basis of the IEEE1394 standard. The driver corresponding to the format of the video camera apparatus is read as a result of the discrimination and, after that, the transmission and reception of the data to/from the video camera apparatus are executed through such a driver until the computer is disconnected (shut off) from the video camera apparatus. Thus, when the computer receives the video/audio signals of the different formats from the video camera apparatus during the reproduction, it is difficult for the driver to cope with such a situation and an inconvenience such as hang-up of the computer itself or the like is caused.
To avoid such a problem, therefore, it is necessary to interrupt the connection between the video camera apparatus and the computer once each time the format of the data to be outputted (reproduced) is changed and connect them again. For such a process, for example, it is necessary to physically pull out or insert the cable.
On the other hand, in JP-B-8-31063, there has been disclosed such a technique that if an information apparatus such as a computer or the like and a peripheral apparatus such as a storing device are connected, when an error signal from the peripheral apparatus is detected, the information apparatus disconnects an interface between both apparatuses while keeping only a part of the interface, and when a recovery signal indicative of the recovery from the error is detected, the interface is connected again.
In JP-A-11-163912, a network control apparatus which can remote-control so that a node connected to an IEEE1394 bus is automatically disconnected from a network has been disclosed.
Further, among the video camera apparatuses which have so far been commercially available and cope with the recording and reproduction of the HDV format and the DV format, there is an apparatus in which the disconnection (shut-off) and re-connection of the IEEE1394 bus are performed by a hardware switch.